The entanglement \(C_{i,i+1}\)  between the nearest two qubits is
plotted in Fig. 1 as a function of the spin site \(i\)  and the time
\(t\)  when \(J_z=1.0\) . The three dimensional entanglement \(C_{i,i+1}\) 
is plot in Fig. 1(a). The contour line is plotted in Fig. 1(b). From
Fig. 1, it is clear that there is an entanglement wall for small
time \(t\) . It seems that the sudden change of \(J_z\)  from extremely
large value (\(J_z\rightarrow +\infty \) ) to a finite value creates the
entanglement wall [1]}, [2]}. The entanglement in the
range of \(10<i<50\)  is quite similar. When the time \(t=0\) , the
entanglement is zero. When the time increases, the entanglement
creates and increases from zero. The entanglement reaches a peak at
the time \(t=0.7\) . When the time increases further, the entanglement
value maintains in the extent \([0,0.1]\) . In Fig. 1, it could also be
seen that when \(i<10\)  and \(50>i\) , the entanglement oscillates
acutely. The maximal value of entanglement is higher than the
maximal value in the extent of \(10<i<50\) . This is due to the effects
of the open boundary condition [3]}, [4]}. From Fig. 1, it
is clear that the entanglement \(C_{i, i+1}\)  is symmetric about
\(i=30\) . This is mainly due to the fact that several sources in a
lattice emit oppositely moving pairs of entangled quasi-particles
[2]}.
